COMPARISONS BETWEEN THE RESPONSE OF GERMAN-COCKROACH FIELD-COLLECTED STRAINS (DICTYOPTERA, BLATTELLIDAE) TO VAPORS AND CONTACT WITH A CYFLUTHRIN FORMULATION

Research on differences in insecticide-induced behavior of German cock roach field-collected strains was continued. Late instar nymphs (5th-6 th stadia) were drawn from the Fairbanks, an insecticide susceptible s train, and two pyrethroid resistant strains, the Jacksonville and Fore st Green. Dispersal induced by vapors of a cyfluthrin flowable concent rate (FC) and the FC formulation base (blank) was compared with respon se to the FC and the FC blank when dry. Jacksonville nymphs avoided th e dried FC, but not as strongly as Fairbanks strain nymphs. The AI pla yed a major role in eliciting avoidance by Fairbanks strain nymphs but , in the Jacksonville strain, avoidance was due more to an ingredient( s) of the formulation base. Forest Green nymphs did not avoid the drie d FC or the FC blank. Vapors of the FC and the FC blank caused rapid d ispersal of all strains, but dispersal of resistant strain nymphs was slower than that of susceptible strain nymphs. Although Jacksonville n ymphs responded more strongly to the dried formulation than Forest Gre en nymphs, the response to vapors was weaker than that of Forest Green nymphs. It is suggested that localized populations of the German cock roach have developed many different combinations of behavioral modific ations and physiological/biochemical resistance.